Sensor, sensor substrate, and sensor manufacturing method

ABSTRACT

A sensor includes a generator configured to generate a predetermined detection target, a detector configured to detect the detection target generated by the generator, and a substrate provided with the generator and the detector. The substrate includes a first portion provided with the generator, a second portion provided with the detector, a bent portion that is bent between the first portion and the second portion such that the generator and the detector face each other, and a ground pattern provided in a portion including the first portion, the second portion, and the bent portion. In the ground pattern, a ground pattern of the bent portion is narrower than a ground pattern of the first portion and a ground pattern of the second portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Stage of PCT international applicationSer. No. PCT/JP2016/055721 filed on Feb. 25, 2016 which designates theUnited States, incorporated herein by reference.

FIELD

The present invention relates to a sensor, a sensor substrate, and asensor manufacturing method.

BACKGROUND

A configuration of accommodating a substrate provided with a lightemitting element emitting light, and a substrate provided with a lightreceiving element detecting the light emitted from the light emittingelement, in a housing of a rotary encoder, has been known as aconfiguration of a rotary encoder (for example, Patent Literature 1).

CITATION LIST Patent Literature

Patent Literature 1: JP 2001-027551 A

Technical Problem

However, in the rotary encoder described in Patent Literature 1, thelight emitting element and the light receiving element are provided inseparate substrates; and thus, in the assembly, it is necessary toperform positioning for determining a relationship between anirradiation region of the light from the light emitting element and alight receiving region of the light receiving element. When a positionaldeviation occurs due to mispositioning, the output of the lightreceiving element does not become an intended output in some cases, thuscausing the output associated with sensing to be unstable. Inparticular, when the rotary encoder includes a plurality of lightreceiving elements, a positional deviation causes variations in theoutputs of the light receiving elements, thus causing the outputsassociated with sensing to be unstable.

Such problems associated with the rotary encoder of Patent Literature 1are not limited to the rotary encoder of light detection, but are commonin sensors including a generator generating a detection target (forexample, light or the like) and a detector detecting the detectiontarget generated by the generator that are provided in separatesubstrates.

An object of an aspect of the present invention is to provide a sensorin which positioning between a generator and a detector is more easilyperformed, and a manufacturing method of the sensor. Further, an objectof an aspect of the present invention is to provide a sensor that ismore easily manufactured, a substrate of the sensor, and a manufacturingmethod of the sensor.

SUMMARY

A sensor according to an aspect of the present invention for attainingthe objects described above includes: a generator configured to generatea predetermined detection target; a detector configured to detect thedetection target generated by the generator; and a substrate providedwith the generator and the detector. The substrate includes a firstportion provided with the generator, a second portion provided with thedetector, a bent portion that is bent between the first portion and thesecond portion such that the generator and the detector face each other,and a ground pattern provided in a portion including the first portion,the second portion, and the bent portion. In the ground pattern, aground pattern of the bent portion is narrower than a ground pattern ofthe first portion and a ground pattern of the second portion.

A sensor substrate according to an aspect of the present invention forattaining the objects described above, is a substrate of a sensorincluding a generator configured to generate a predetermined detectiontarget, a detector configured to detect the detection target generatedby the generator, and the substrate provided with the generator and thedetector, the substrate including: a first portion provided with thegenerator; a second portion provided with the detector; a bent portionthat is bent between the first portion and the second portion such thatthe generator and the detector face each other; and a ground patternprovided in a portion including the first portion, the second portion,and the bent portion. In the ground pattern, a ground pattern of thebent portion is narrower than a ground pattern of the first portion anda ground pattern of the second portion.

A sensor manufacturing method according to an aspect of the presentinvention for attaining the objects described above, is a manufacturingmethod of a sensor including a generator configured to generate apredetermined detection target, a detector configured to detect thedetection target generated by the generator, and a substrate providedwith the generator and the detector, the method including: a step ofpreparing the substrate including a first portion provided with thegenerator, a second portion provided with the detector, a bent portionto be bent between the first portion and the second portion such thatthe generator and the detector face each other, and a ground patternprovided in a portion including the first portion, the second portion,and the bent portion; and a step of bending the substrate in the bentportion. In the ground pattern, a ground pattern of the bent portion isnarrower than a ground pattern of the first portion and a ground patternof the second portion.

Accordingly, the first portion provided with the generator and thesecond portion provided with the detector are not separated from eachother, thereby positioning the generator and the detector by a simpleoperation of bending or curving the substrate. Thus, according to thesensor of the aspect of the present invention, the positioning betweenthe generator and the detector is more easily performed. Further, in theground pattern, the ground pattern of the bent portion is narrower thanthe ground pattern of the first portion and the ground pattern of thesecond portion, thereby bending the bent portion more easily than otherportions, with respect to a condition such as the elasticity and therigidity of the substrate. Consequently, the sensor can be more easilymanufactured.

In the sensor of the aspect of the present invention, the substrateincludes a connection portion connecting the first portion and thesecond portion together, and the bent portion is provided between theconnection portion and the first portion, and between the connectionportion and the second portion.

Accordingly, the connection portion provides a region between the firstportion and the second portion. Thus, a region between the generator andthe detector is more easily provided.

In the sensor of the aspect of the present invention, the ground patternis further provided in a portion including the connection portion, and,in the ground pattern, the ground pattern of the bent portion isnarrower than a ground pattern of the connection portion.

Accordingly, the bent portion can be bent more easily than otherportions, with respect to the condition such as the elasticity and therigidity of the substrate. Thus, the sensor is manufactured more easily.

In the sensor of the aspect of the present invention, the substrate is aflexible printed circuit.

Accordingly, it is possible to more easily perform a series ofoperations of mounting components including the generator and thedetector on the substrate, in a state where the first portion and thesecond portion exist in the same plane, and then, of processing thesubstrate in order to provide a detection region between the generatorand the detector.

In the sensor of the aspect of the present invention, the sensor is arotary encoder.

Therefore, according to an aspect of the present invention, it ispossible to detect an angle position such as a turning angle of aturning motion body connected to the rotary encoder.

Advantageous Effects of Invention

According to the sensor, the sensor substrate, and the sensormanufacturing method, of an aspect of the present invention, thepositioning between the generator and the detector is performed moreeasily. Further, according to the sensor, the sensor substrate, and thesensor manufacturing method, of an aspect of the present invention, thesensor is more easily manufactured.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram of a sensor according to oneembodiment of the present invention.

FIG. 2 is an external perspective view of the sensor.

FIG. 3 is an explanatory diagram illustrating an example of anarrangement of a generator, an optical scale, and a detector.

FIG. 4 is a block diagram of an optical encoder.

FIG. 5 is an explanatory diagram illustrating an example of a pattern ofthe optical scale.

FIG. 6 is a perspective view illustrating an example of a substrate.

FIG. 7 is a plan view illustrating an example of the substrate beforebeing bent.

FIG. 8 is a diagram illustrating an example of a correspondencerelationship between a circuit arrangement on a surface where thegenerator and the detector are provided, and a configuration provided ona rear surface.

FIG. 9 is a diagram illustrating an example of a ground pattern of thesubstrate.

FIG. 10 is a perspective view illustrating an example of a body of astator, and a configuration provided on the body.

FIG. 11 is a perspective view illustrating an example of a configurationprovided on a chassis of the stator.

FIG. 12 is a diagram illustrating an example of a position relationshipbetween the generator and the detector.

FIG. 13 is a diagram illustrating an example of the positionrelationship between the generator and the detector.

FIG. 14 is a plan view illustrating an example of the substrate before acircuit is mounted thereon.

FIG. 15 is a diagram illustrating an example of the assembly of thestator for providing the optical scale in a detection region.

FIG. 16 is a diagram illustrating an example of the assembly of thestator for providing the optical scale in the detected region.

FIG. 17 is an explanatory diagram for illustrating an example of thedetector.

FIG. 18 is an explanatory diagram for illustrating an example of a firstlight receiver of the detector.

FIG. 19 is an explanatory diagram for illustrating an example of a thirdlight receiver of the detector.

FIG. 20 is an explanatory diagram for illustrating the separation of apolarization component according to the optical scale.

FIG. 21 is an explanatory diagram for illustrating the separation of thepolarization component according to the optical scale.

FIG. 22 is an explanatory diagram for illustrating the separation of thepolarization component according to the optical scale.

FIG. 23 is a functional block diagram of the optical encoder.

FIG. 24 is an explanatory diagram for illustrating a rotation angle ofthe optical scale and a light intensity change of the polarizationcomponent of each of the light receivers.

FIG. 25 is an explanatory diagram for illustrating a relationshipbetween the rotation angle of the optical scale and a Lissajous angle.

FIG. 26 is a diagram for illustrating the generator.

FIG. 27 is a diagram illustrating an example of a relationship between ageneration region of light from the generator and the positions of thedetector and a shaft.

FIG. 28 is a flowchart of an exemplary process of manufacturing thesensor.

FIG. 29 is a diagram illustrating another arrangement example of aplurality of light receiving elements of the detector.

DESCRIPTION OF EMBODIMENTS

A mode (an embodiment) for carrying out the present invention will bedescribed in detail with reference to the drawings. The presentinvention is not limited to the contents described in the followingembodiment. Constituents in the following description include thoseeasily conceivable by a person skilled in the art and thosesubstantially identical thereto. Further, the constituents in thefollowing description can be combined as appropriate.

FIG. 1 is a configuration diagram of a sensor 31 according to oneembodiment of the present invention. FIG. 2 is an external perspectiveview of the sensor 31. FIG. 1 is a schematic diagram illustrating asectional configuration of FIG. 2. FIG. 3 is an explanatory diagramillustrating an example of an arrangement of a generator 41, an opticalscale 11, and a detector 35. FIG. 4 is a block diagram of an opticalencoder 2. FIG. 5 is an explanatory diagram illustrating an example of apattern of the optical scale 11. The sensor 31 includes the generator 41generating a detection target that is an electromagnetic wave (forexample, light), the detector 35 detecting the detection targetgenerated by the generator 41 provided with a detection regiontherebetween, and a substrate 50 provided with the generator 41 and thedetector 35. In this embodiment, the sensor 31 further includes a rotor10 and a stator 20. The rotor 10 includes a shaft 12 and a motion body(the optical scale 11). The shaft 12 is connected to a rotary machinesuch as a motor. The motion body (the optical scale 11) is attached toan end portion of the shaft 12 and provided to be rotatable in thedetection region. Furthermore, the detection region is a space betweenthe generator 41 and the detector 35. The generator 41 in thisembodiment includes a light emitting element that emits light. Thedetector 35 in this embodiment is a light receiving element thatreceives the light emitted from the generator 41 serving as the lightemitting element. More specifically, the detector 35 of this embodimentincludes four light receiving elements of a first light receiver PD1including a polarization layer PP1, a second light receiver PD2including a polarization layer PP2, a third light receiver PD3 includinga polarization layer PP3, and a fourth light receiver PD4 including apolarization layer PP4. In order to describe that incident light 73,which travels toward the light receivers (the first light receiver PD1to the fourth light receiver PD4) from source light 71 generated by thegenerator 41, passes through the respective polarization layers PP1 toPP4, the polarization layers PP1 to PP4 are illustrated apart from thefirst light receiver PD1 to the fourth light receiver PD4 in FIG. 3. Therespective polarization layers and the light receivers, however,actually abut on each other.

FIG. 6 is a perspective view illustrating an example of the substrate50. FIG. 7 is a plan view illustrating an example of the substrate 50before being bent. FIG. 8 is a diagram illustrating an example of acorrespondence relationship between a circuit arrangement on a surfacewhere the generator 41 and the detector 35 are provided, and aconfiguration provided on a rear surface. FIG. 9 is a diagramillustrating an example of a ground pattern of the substrate 50. FIG. 10is a perspective view illustrating an example a body 21 of the stator20, and a configuration provided on the body 21. FIG. 11 is aperspective view illustrating an example of a configuration provided ona chassis 22 of the stator 20. FIG. 12 and FIG. 13 are diagramsillustrating an example of a position relationship between the generator41 and the detector 35. FIG. 14 is a plan view illustrating an exampleof the substrate before a circuit is mounted thereon. FIG. 15 and FIG.16 are diagrams illustrating an example of the assembly of the stator 20for providing the optical scale 11 in the detection region. FIG. 17 isan explanatory diagram for illustrating an example of the detector 35.The substrate 50 is configured such that a first portion 51 providedwith the generator 41 and a second portion 52 provided with the detector35 are integrated with each other. For example, as illustrated in FIG. 6and FIG. 7, the substrate 50 is one substrate including the semicirculararc-like first portion 51 and the circular second portion 52. Thesubstrate 50 is, for example, a flexible printed circuit (FPC). Variouscircuits (for example, an IC circuit 60 illustrated in FIG. 6, or thelike) including the generator 41 and the detector 35 are mounted on thesubstrate 50. More specifically, the FPC is, for example, a wiringsubstrate having flexibility obtained by using an insulating body suchas a polyimide film or a photo-solder resist film, as a base film, byforming an adhesive layer and a conductor layer on the base film, and bycovering, with the insulating body, a portion of the conductor layerexcept for a terminal portion (including a soldering portion). Theconductor layer is an electrical conductor such as copper. Patterns onthe conductor layer form a signal line, a power line, a ground pattern80, and the like, to be connected to components such as variouscircuits. A specific configuration of a flexible substrate that can beused in the embodiment of the present invention is not limited thereto,and can be changed as appropriate. Various circuits such as the ICcircuit 60, except for the detector 35 and the generator 41, configure apre-amplifier AMP, a differential operational circuit DS, a filtercircuit NR, a multiplication circuit AP, and the like, illustrated inFIG. 23 described below. Hereinafter, a surface of the substrate 50 on aside where the generator 41 and the detector 35 are provided, may bereferred to as a front surface 50A, and a surface on the opposite sidemay be referred to as a rear surface 50B (refer to FIG. 8). In the frontsurface 50A of the substrate 50, a front surface 51A of the firstportion 51 and a front surface 52A of the second portion may bedistinctively described. In the rear surface 50B of the substrate 50, arear surface 51B of the first portion 51 and a rear surface 52B of thesecond portion 52 may be distinctively described.

A plate-like support member is provided in the substrate 50. The supportmember keeps a surface, on which an electronic component is provided,flat. The support member is attached to a surface on a rear side of atleast one of a surface of the first portion 51 on which an electroniccomponent including the generator 41 is provided and a surface of thesecond portion 52 on which an electronic component including thedetector 35 is provided. Specifically, as illustrated in, for example,FIG. 7, a component 61 is provided on the same surface (the frontsurface 52A) in the second portion 52 as that on which the lightreceiving elements are provided. In addition to photodiodes (the firstlight receiver PD1 to the fourth light receiver PD4) constituting thelight receiving elements, the component 61 is provided inside a mountingregion of the IC circuit 60 on the rear surface 52B on the opposite sideof the front surface 52A. The component 61 is a component other than thelight receiving elements and provided on the same surface (the frontsurface 52A) in the second portion 52 as that on which the lightreceiving elements are provided, and specifically, includes a circuitcomponent such as an IC chip, a resistor, and a capacitor. The ICcircuit 60 is, for example, an integrated circuit to which a quad flatno lead package (QFN) is adopted. Thus, a support member of the secondportion 52 in this embodiment is a package of an integrated circuit (theIC circuit 60). One or more electronic components (for example, thedetector 35 and the component 61) to be provided in the second portion52 to which the package is attached, are provided on a rear side of thesubstrate 50 opposite to the side thereof on which the package isprovided, and arranged in a position corresponding to a position wherethe package is arranged. The package of the integrated circuit is notlimited to the QFN package, and it may be any package that provides aconfiguration including a support structure portion capable offunctioning as a support member for keeping a surface on a side oppositeto a surface on which the integrated circuit is provided (for example,the front surface 52A of the second portion 52) flat. Furthermore, inthis embodiment, the component 61 such as an IC chip, a resistor, and acapacitor, which is the other circuit to be provided on the frontsurface 52A of the second portion 52, includes a package circuit that isconnected to wiring by soldering, and a bare chip that is connected towiring by a method such as wire bonding. However, such a configurationis merely an example, and the component 61 is not limited to theconfiguration. The component 61 may be either one of the package circuitor the bare chip, or may be a circuit of which a part or all parts areprovided using other packaging technologies.

As illustrated in FIG. 8, in the first portion 51 of this embodiment, asupport substrate 65 is provided on a rear side of a surface on whichthe light emitting element packaged with a light emitting device 41U(refer to FIG. 26) is provided. The support substrate 65 is, forexample, a semicircular arc-like plate member corresponding to thesemicircular arc-like first portion 51. More specifically, the firstportion 51 and the support substrate 65 include a semicircular arc-likeplate surface corresponding to one of two semicircular arc-like platesurfaces obtained by dividing a donut-like (circular arc-like) platesurface, in which a circular hole is provided at the center of a surfaceof a circular plate, into two along the diameter, the circular holehaving a diameter smaller than that of the circular plate. The supportsubstrate 65 is formed of, for example, a resin having insulatingproperties. Thus, a support member of the first portion 51 in thisembodiment is a plate-like member having insulating properties, which isformed corresponding to the shape of the first portion 51. The supportsubstrate 65 in this embodiment is merely an example of the supportmember other than a circuit and not limited thereto. The support membercan be changed as appropriate.

The substrate 50 includes a connection portion 53 connecting the firstportion 51 and the second portion 52 together. Specifically, forexample, as illustrated in FIG. 6 and FIG. 7, the connection portion 53is provided between the first portion 51 and the second portion 52 suchthat a circular arc-like outer circumferential portion of the firstportion 51 and a circular arc-like outer circumferential portion of thesecond portion 52 are connected together.

The connection portion 53 includes wiring that is connected to thegenerator 41 (or the detector 35). In this embodiment, the connectionportion 53 includes a signal line and a power line that are connected tothe generator 41. Specifically, the wiring of the connection portion 53is provided as a signal line and a power line mounted on the FPC, forexample. Furthermore, a circuit is not provided in the connectionportion 53 of this embodiment, but a component such as a circuit can beprovided in the connection portion 53.

As illustrated in FIG. 6 and FIG. 7, the connection portion 53 of thisembodiment has a smaller width in a direction along the plate surface ofthe substrate 50 and orthogonal to an extending direction of theconnection portion 53 between the first portion 51 and the secondportion 52, than the first portion 51 and the second portion 52.

The substrate 50 includes a harness portion 54 including wiring that isconnected to the generator 41 and the detector 35. Specifically, forexample, as illustrated in FIG. 6 and FIG. 7, the harness portion 54 isprovided to extend from the first portion 51 to a side opposite to theconnection portion 53. The harness portion 54 includes a signal line anda power line that are connected to the generator 41, the detector 35,and various circuits provided on the substrate 50. Specifically, thewiring of the harness portion 54 is provided as a signal line and apower line mounted on the FPC, for example. In this embodiment, thewiring of the generator 41 is provided in the first portion 51, theconnection portion 53, and the harness portion 54. The wiring of thedetector 35 is provided in the second portion 52 and the harness portion54.

The harness portion 54 may be connected to a connector CNT, asillustrated in, for example, FIG. 1. The connector CNT is an interfaceconnecting the sensor 31 and other devices (for example, an arithmeticdevice 3) together. The sensor 31 is connected to the arithmetic device3 through the connector CNT. That is, the harness portion 54 functionsas wiring connecting various circuits provided on the substrate 50 andother devices (for example, the arithmetic device 3) together.Furthermore, the harness portion 54 may be provided with a componentsuch as a circuit. The connector CNT can be omitted. In this case, a tipend of the harness portion 54 is provided as, for example, a terminalthat is inserted into a connector (not illustrated) provided on a deviceto which the sensor 31 is connected.

The substrate 50 is provided such that the first portion 51 and thesecond portion 52 are parallel to each other. Specifically, thesubstrate 50 is bent such that the substrate 50 is bent into a shape (aU-shape) where the generator 41 and the detector 35 face each other, asillustrated in FIG. 1 and FIG. 6. In this embodiment, the substrate 50is bent at a right angle at each of a bent portion 55 a between theconnection portion 53 and the first portion 51 and a bent portion 55 bbetween the connection portion 53 and the second portion 52 such thatthe front surface 50A is inside. That is, the substrate 50 is bent suchthat the first portion 51 and the second portion 52 are each at a rightangle with respect to the connection portion 53, and the first portion51 and the second portion 52 face each other. Accordingly, the firstportion 51 and the second portion 52 are provided parallel to eachother, and the generator 41 and the detector 35 face each other. Thus,the substrate 50 includes the bent portions 55 a and 55 b that are bentbetween the first portion 51 and the second portion 52 such that thegenerator 41 and the detector 35 face each other. In this embodiment,the bent portions 55 a and 55 b are respectively provided between theconnection portion 53 and the first portion 51, and between theconnection portion 53 and the second portion 52.

A surface on a side where the generator 41 is provided in the firstportion 51, and a surface on a side where the detector 35 is provided inthe second portion 52, are the same surface (the front surface 50A) inthe substrate 50. The surface on a side where the generator 41 isprovided and the surface on a side where the detector 35 is provided,are provided to face each other. Thus, as illustrated in FIG. 3 andother figures, a position relationship between the generator 41 and thedetector 35 is a position relationship allowing the detection target(for example, light) generated by the generator 41 to be detected by thedetector 35. The space between the generator 41 and the detector 35facing each other is the detection region.

Thus, in the substrate 50, the first portion 51 provided with thegenerator 41, the second portion 52 provided with the detector 35, andthe connection portion 53 connecting the first portion 51 and the secondportion 52 together are integrated with each other. Further, thesubstrate 50 is bent at a right angle at each of the two bent portions55 a and 55 b, so that the surface of the first portion 51 on which thegenerator 41 is provided (the front surface 51A) and the surface of thesecond portion 52 on which the detector 35 is provided (the frontsurface 52A) are provided parallel to and facing each other. Here, asillustrated in FIG. 7, a first axis LA serving as a bending axis of thebent portion 55 a is parallel to a second axis LB serving as a bendingaxis of the bent portion 55 b. The bending axis indicates an axisserving as, when the substrate 50 is bent, a motion center axis of abending motion of one portion (for example, the connection portion 53)with respect to another portion (for example, the first portion 51 orthe second portion 52) that face the one portion with a bending portion(for example, the bent portions 55 a and 55 b) of the substrate 50therebetween. The first axis LA and the second axis LB in thisembodiment are respectively located in positions overlapping two bendinglines formed as bending places in the bent portions 55 a and 55 b on thesubstrate 50.

The substrate 50 includes the ground pattern provided in a portionincluding the first portion 51, the second portion 52, and the bentportions 55 a and 55 b. In the ground pattern 80, a ground pattern 81 ofthe bent portions 55 a and a ground pattern 82 of the bent portion 55 bare narrower than a ground pattern 83 of the first portion 51 and aground pattern 84 of the second portion 52. In this embodiment, theground pattern 80 is further provided in a portion including theconnection portion 53. In the ground pattern 80, the ground pattern 81of the bent portion 55 a and the ground pattern 82 of the bent portion55 b are narrower than a ground pattern 85 of the connection portion 53.Specifically, the substrate 50 includes a rolled copper foil or thelike, as the ground pattern 80. The ground pattern 80 is electricallyconnected to various electronic components provided on the substrate 50such as the generator 41, the detector 35, and the IC circuit 60. Thepotential of the ground pattern 80 functions as a reference of thepotential of the electronic components. The ground pattern 80 is coveredexcept for the terminal portion (including the soldering portion)connected to the electronic circuits. For example, as illustrated inFIG. 9, the maximum widths of the ground patterns 81 and 82 of the bentportions 55 a and 55 b included in the ground pattern 80, in a directionalong the bending axes LA and LB, are narrower than the maximum widthsof the ground pattern 83 of the first portion 51, the ground pattern 84of the second portion 52, and the ground pattern 85 of the connectionportion 53.

The ground pattern 80 of this embodiment has a uniform thickness. Thatis, the thicknesses of the ground patterns 81 to 85 of the bent portions55 a and 55 b, the first portion 51, the second portion 52, and theconnection portion 53 are equal to each other. The ground pattern 80 ofthis embodiment has a single plate structure in which the first portion51 to the harness portion 54 are arranged continuously without anyinterruption. Such specific configuration relevant to the thickness andthe structure of the ground pattern 80 is merely an example. Theconfiguration is not limited thereto and can be changed as appropriate.For example, in a case where the thickness of the ground pattern 80 isnot made to be uniform, the ground patterns 81 and 82 of the bentportions 55 a and 55 b can be formed to be thinner than the groundpattern of the other portion, and thus, the bending in the bent portions55 a and 55 b is performed more easily.

On the plane before the substrate 50 is bent, a distance between a firstpoint and the first axis LA is equal to a distance between a secondpoint and the second axis LB. The first point is a generation centerpoint of the detection target of the generator 41, and the second pointis either one of the center of a detection region of the detectiontarget of the detector 35 or an arrangement center of a plurality ofdetection regions of the detector 35. Specifically, as illustrated inFIG. 7, a distance W1 is equal to a distance W2. In this embodiment, thedistance W1 is a distance between an emitting point 41S of the lightgenerated by the generator 41 and the first axis LA serving as thebending line in the bent portion 55 a, and the distance W2 is a distancebetween an arrangement center S0 of the four light receiving elements ofthe detector 35, that is, the first light receiver PD1, the second lightreceiver PD2, the third light receiver PD3, and the fourth lightreceiver PD4, and the second axis LB serving as the bending line in thebent portion 55 b. Here, the emitting point 41S of the light generatedby the generator 41 is the first point in this embodiment, and thearrangement center S0 is the second point in this embodiment.

The first point and the second point are located on the same straightline along the substrate 50 before being bent, and the straight lineintersects each of the first axis LA and the second axis LB at a rightangle. The first point and the second point are located on the samestraight line orthogonal to the first axis LA and the second axis LB.Specifically, as illustrated in FIG. 7, the emitting point 41S of thelight generated by the generator 41 and the arrangement center S0 arelocated on a straight line L1 that is the same straight line orthogonalto two bending lines in the bent portions 55 a and 55 b, that is, thefirst axis LA and the second axis LB.

The four light receiving elements are arranged in different positions ona predetermined plane. The four light receiving elements are arranged atequal distances from one point on the predetermined plane. Four linesegments connecting one point and the respective centers of lightreceiving regions of the four light receiving elements form right angleswith each other. Specifically, the first light receiver PD1, the secondlight receiver PD2, the third light receiver PD3, and the fourth lightreceiver PD4, which are the four light receiving elements of thedetector 35, are arranged at the same distance from one point (thearrangement center S0) on the front surface 52A of the second portion 52of the substrate 50. On the front surface 52A, the first light receiverPD1 and the third light receiver PD3 are arranged in a point-symmetricposition with respect to the arrangement center S0, and the second lightreceiver PD2 and the fourth light receiver PD4 are arranged in apoint-symmetric position with respect to the arrangement center S0. Inthis embodiment, the light receiving regions of the first light receiverPD1, the second light receiver PD2, the third light receiver PD3, andthe fourth light receiver PD4 are the same in shape and area. Thedetector 35 is arranged such that the center of the light receivingregion of the first light receiver PD1 and the center of the lightreceiving region of the third light receiver PD3 are arranged atdistance of 2 W with the arrangement center S0 as a center therebetween,and the center of the light receiving region of the second lightreceiver PD2 and the center of the light receiving region of the fourthlight receiver PD4 are arranged at distance of 2 W with the arrangementcenter S0 as a center therebetween. In other words, the distancesbetween the centers of the light receiving regions of the four lightreceiving elements of the first light receiver PD1 to the fourth lightreceiver PD4, and the arrangement center S0, are the same as a distanceW. Furthermore, in this embodiment, the distance W from the center ofthe light receiving regions of the first light receiver PD1, the secondlight receiver PD2, the third light receiver PD3, and the fourth lightreceiver PD4 to the arrangement center S0, is greater than a width w ofthe first light receiver PD1, the second light receiver PD2, the thirdlight receiver PD3, and the fourth light receiver PD4. In a case where avirtual axis passing through the center of the light receiving region ofthe first light receiver PD1, the arrangement center S0, and the centerof the light receiving region of the third light receiver PD3 is set toan x axis, and a virtual axis passing through the center of the lightreceiving region of the second light receiver PD2, the arrangementcenter S0, and the center of the light receiving region of the fourthlight receiver PD4 is set to a y axis, the x axis and the y axis areorthogonal to each other on the front surface 52A of the second portion52. That is, on the front surface 52A of the second portion 52, an angleθ1 formed by the center of the light receiving region of the first lightreceiver PD1 and the center of the light receiving region of the secondlight receiver PD2, is 90°. Similarly, an angle θ2 formed by the centerof the light receiving region of the second light receiver PD2 and thecenter of the light receiving region of the third light receiver PD3, anangle θ3 formed by the center of the light receiving region of the thirdlight receiver PD3 and the center of the light receiving region of thefourth light receiver PD4, and an angle θ4 formed by the center of thelight receiving region of the fourth light receiver PD4 and the centerof the light receiving region of the first light receiver PD1, are 90°.Thus, the first light receiver PD1, the second light receiver PD2, thethird light receiver PD3, and the fourth light receiver PD4 are equallyarranged at 90° intervals, on the same circumference with thearrangement center S0 as the center of a circle, on the front surface52A. An xy plane of the x axis and the y axis is orthogonal to a z axisconnecting the emitting point 41S of the light generated by thegenerator 41 and the arrangement center S0. That is, in a case where thefront surface 52A is viewed from the generator 41 side along a z axisdirection, the emitting point 41S overlaps with the arrangement centerS0. That is, a straight line L2 (refer to FIG. 13), which is a normalline of a predetermined plane (for example, the front surface 52A of thesecond portion 52) passing through one point (the arrangement centerS0), passes through the center of the emitting point 41S of the lightgenerated by the generator 41. Thus, the first light receiver PD1, thesecond light receiver PD2, the third light receiver PD3, and the fourthlight receiver PD4 are arranged at the same distance from the emittingpoint 41S of the light emitted from the generator 41.

The detector 35 detects changes in the detection target (for example, anelectromagnetic wave such as light), which occurs due to changes in aphysical amount in the detection region. The changes in the physicalamount, for example, occur due to the rotation of the motion bodyexisting in the detection region. Specifically, for example, asillustrated in FIG. 1 to FIG. 3, the optical scale 11 of the rotor 10 isprovided in the detection region. The sensor 31 is a sensor performingoutput depending on a change in a detection result of the detectiontarget due to the rotation of the optical scale 11 as the motion body.That is, the sensor 31 functions as a rotary encoder detecting anglepositions of a turning motion body on the rotor 10. In this embodiment,the sensor 31 detects rotation angles of the rotating body connected tothe rotor 10, but the sensor 31 is capable of detecting not only therotation angles of the rotating body, but also turning angles of theturning motion body that is turned in a range of less than 360°.

One of the first portion 51 and the second portion 52 is smaller thanthe other. Specifically, for example, as illustrated in FIG. 6 and FIG.7, the diameter of the circular arc-like first portion 51 in thisembodiment is substantially equal to the diameter of the circular secondportion 52. However, the first portion 51 is in the shape of asemicircular arc in which a semicircular cut-out portion 51 a isprovided on an inner circumference side of a semicircular FPC. For thisreason, the area of the first portion 51 in the substrate 50 is smallerthan the area of the second portion 52. The cut-out portion 51 a isprovided to set the shaft 12 and the substrate 50 to be in a non-contactstate.

The rotor 10 includes the optical scale 11 that is a member having acircular plate shape illustrated in FIG. 5 (or a polygonal shape). Theoptical scale 11, for example, is formed of silicon, glass, a polymermaterial, and the like. The optical scale 11 illustrated in FIG. 5includes a signal track T1 on one plate surface. The rotor 10 has aplate surface to which the shaft 12 is attached and the other platesurface to which the optical scale 11 is attached. In a case where theoptical scale 11 is inclined, but an inclination angle is small, apolarization separation function is not affected. The optical scale 11in this embodiment functions as a member affecting light by being movedin the detection region that is the space between the generator 41 andthe detector 35. The optical scale 11, which is the motion body in thisembodiment, is a disk-like member that is rotatably supported throughthe shaft, but the disk-like member is merely an example of the opticalscale 11, and the optical scale 11 is not limited thereto. The shape orthe like thereof can be changed as appropriate.

The stator 20 includes a member having light shielding properties, whichsurrounds bearings 26 a and 26 b, the shaft 12, the optical scale 11attached to the end portion of the shaft 12, and the detector 35. Thus,the external optical noise in the stator 20 is suppressed. The stator 20in this embodiment functions as a housing containing the substrate 50and the member (the optical scale 11). The housing includes a firstmember to which a part of the substrate 50 is fixed, and a second membersupporting the member such that the member can be moved. Specifically,the stator 20 includes the body 21 functioning as the second member, thechassis 22 functioning as the first member, and a cover 23. The body 21is a housing rotatably supporting the shaft 12 through the bearings 26 aand 26 b. An inner circumference of the body 21 is fixed to outer ringsof the bearings 26 a and 26 b, and an outer circumference of the shaft12 is fixed to inner rings of the bearings 26 a and 26 b. When the shaft12 is rotated in accordance with the rotation of a rotary machine suchas a motor, the optical scale 11 rotates about a rotation center Zr asan axis center, in tandem with the shaft 12. The body 21 has an openingportion 21 a for attaching the chassis 22 on which the substrate 50 isprovided, to the body 21. The substrate 50 is fixed to the chassis 22 toabut on at least a part of the surface on a side opposite to the surfaceon which the detector 35 is provided (the rear surface), of the secondportion 52 of the substrate 50. Specifically, as described above, the ICcircuit 60 is provided on the rear surface 50B of the substrate 50, as acomponent included in the sensor 31. The chassis 22, for example, asillustrated in FIG. 11, is shaped to cover the IC circuit 60 of the rearsurface from the outside and abut on a circular outer circumferentialportion of the second portion 52. The connection portion 53 of thesubstrate 50, which is bent into a U-shape, is fixed to the chassis 22,and thus, is positioned to be erect from the second portion 52 supportedon the chassis 22. Thus, in this embodiment, the second portion 52 isfixed to the chassis 22, and thus, the substrate 50 is fixed to thechassis 22. The cover 23 is a member forming a part of a cylindricalouter circumferential surface of the stator 20. The cover 23 is providedon an opening portion 21 a side of the body 21, that is, on a sideopposite to a side where a cut-out portion 21 b is formed, the cut-outportion 21 b being a portion where the harness portion 54 extends fromthe chassis 22. In a state where the body 21 and the chassis 22 areassembled, the cover 23 is further assembled to cover the openingportion 21 a, and thus, the body 21, the chassis 22, and the cover 23form a cylindrical stator 20, and the inside of the stator 20 isshielded from the external optical noise. Thus, the chassis 22 and thecover 23 function as a lid of the body 21 serving as the housing.

The surface of the first portion 51 on a side opposite to a side facingthe detection region adheres to the second member (for example, the body21). Specifically, the surface (the rear surface 51B) of the firstportion 51 on the side opposite to the side facing the detection regionadheres to the second member through a plate-like member (for example,the support substrate 65). More specifically, a tape having a surfaceabutting on the first portion 51 and a surface on the opposite sidethereof, both of which have adhesiveness, is attached to the supportsubstrate 65 of this embodiment. The tape is a so-called double-facedtape, and both surfaces have adhesiveness. That is, one surface of thesupport substrate 65 adheres to the surface (the rear surface 51B) ofthe first portion 51 on the rear side through the tape. In a state whereone surface of the support substrate 65 adheres to the first portion 51,the other surface of the support substrate 65 is in a state of havingadhesiveness. The other surface is a surface where the shaft 12 extendsfrom the body 21 and adheres to a surface (hereinafter, referred to asan adhesive surface 21 c) located on the chassis 22 side through thetape. Thus, one (in this embodiment, the second portion 52) of the firstportion 51 and the second portion 52 is fixed to the first member (thechassis 22). A surface of the other (in this embodiment, the firstportion 51) of the first portion 51 and the second portion 52 on a sideopposite to a side facing the detection region, adheres to the body 21.In a state where one surface of the plate-like member (for example, thesupport substrate 65) adheres to the surface (the rear surface 51B) ofthe other of the first portion 51 and the second portion 52 on the sideopposite to the side facing the detection region, the other surface ofthe plate-like member adheres to the body 21. Furthermore, it ispreferred that the plate-like member (for example, the support substrate65) interposed between the surface (for example, the rear surface 51B)of the other (for example, the first portion 51) of the first portion 51and the second portion 52 on the side opposite to the side facing thedetection region, and the second member (for example, the body 21), haverigidity higher than that of the substrate 50.

In this embodiment, the surface of the first portion 51 on the sideopposite to the side facing the detection region adheres to the secondmember through the support substrate 65. However, such a configurationis merely an example of a specific configuration of adhesion, and is notlimited thereto. For example, the rear surface 51B of the first portion51 may adhere to the adhesive surface 21 c through an adhesive agent ora tape (a double-faced tape or the like). Specifically, for example, theadhesive agent may be applied to several points in the vicinity of anouter circumference of the support substrate 65 or an innercircumferential portion thereof, the support substrate 65 and the rearsurface 51B of the first portion 51 may be spot-fixed, and the supportsubstrate 65 and the adhesive surface 21 c may be spot-fixed. In thespot fixing, the tape may be further used as reinforcement until theadhesive agent is solidified.

In the case of using the adhesive agent, it is only required that theadhesive agent be applied to the second member (for example, the body21) or to the surface of the other of the first portion 51 and thesecond portion 52 on the side opposite to the side facing the detectionregion, and then the second member be allowed to abut on the otherthereof to cause the surface of the other on the side opposite to theside facing the detection region to adhere to the second member.Consequently, the assembly of the sensor 31 is more easily performed.

When the shaft 12 of the rotor 10 described above is rotated, asillustrated in FIG. 3, the optical scale 11 is relatively moved, forexample, in an R direction with respect to the detector 35.Consequently, the signal track T1 of the optical scale 11 is relativelymoved with respect to the detector 35. In the optical scale 11, apolarization direction Pm of a polarizer in the plane is directed in apredetermined direction, and the polarization direction Pm is changed inaccordance with a rotation. The detector 35 reads out the signal trackT1 of the optical scale 11 illustrated in FIG. 5 by receiving theincident light (transmitted light) 73 incident on the detector 35, whichis light obtained by allowing the source light 71 generated by thegenerator 41 to transmit through the optical scale 11.

The optical encoder 2 includes the sensor 31 and the arithmetic device3. As illustrated in FIG. 4, the sensor 31 and the arithmetic device 3are connected to each other. The arithmetic device 3 is connected to acontroller 5 of the rotary machine such as the motor.

The optical encoder 2 allows the detector 35 to detect the incidentlight 73 incident on the detector 35, which is light obtained byallowing the source light 71 to transmit through the optical scale 11.The arithmetic device 3 calculates a relative position between the rotor10 of the sensor 31 and the detector 35 based on a detection signal ofthe detector 35 and outputs information on the relative position, as acontrol signal, to the controller 5 of the rotary machine such as themotor.

The arithmetic device 3 is, for example, a computer such as a personalcomputer (PC). The arithmetic device 3 includes an input interface 4 a,an output interface 4 b, a central processing unit (CPU) 4 c, a readonly memory (ROM) 4 d, a random access memory (RAM) 4 e, and an internalstorage device 4 f. The input interface 4 a, the output interface 4 b,the CPU 4 c, the ROM 4 d, the RAM 4 e, and the internal storage device 4f are connected to each other through an internal bus. Furthermore, thearithmetic device 3 may be configured of a dedicated processing circuit.

The input interface 4 a receives an input signal from the detector 35 ofthe sensor 31 and outputs the input signal to the CPU 4 c. The outputinterface 4 b receives a control signal from the CPU 4 c and outputs thecontrol signal to the controller 5.

The ROM 4 d stores a program such as a basic input output system (BIOS).The internal storage device 4 f is, for example, a hard disk drive(HDD), a flash memory, or the like and stores an operating systemprogram or an application program. The CPU 4 c implements variousfunctions by executing the programs stored in the ROM 4 d or theinternal storage device 4 f while using the RAM 4 e as a work area.

The internal storage device 4 f stores a database in which thepolarization direction Pm of the optical scale 11 is associated with theoutput of the detector 35. Alternatively, the internal storage device 4f stores a database in which the value of a distance D (refer to FIG.13) between the emitting point 41S of the light generated by thegenerator 41 and the arrangement center S0 (the detector 35) isassociated with position information of the optical scale 11.

The signal track T1 illustrated in FIG. 5 is configured such that thearrangement of metal fine lines (wires) g that are referred to as a wiregrid pattern, is formed on the optical scale 11 illustrated in FIG. 1.In the optical scale 11, adjacent metal fine lines g are linearlyarranged parallel to each other, as the signal track T1. Thus, theoptical scale 11 has the same polarization axis obtained regardless ofthe position to which the source light 71 is applied, and thepolarization direction of the polarizer in the plane is directed in onedirection.

The optical scale 11 including the metal fine lines g that are referredto as a wire grid pattern increases heat resistance, as compared to aphotoinduction type polarization plate. The optical scale 11 locally hasa line pattern in which there are no portions that intersect with eachother, and thus, the optical scale 11 with high accuracy and less erroris obtained. Further, the optical scale 11 can be stably manufactured bybatch exposure or a nanoimprint technology, and thus, the optical scale11 with high accuracy and less error is obtained. Furthermore, theoptical scale 11 may be a photoinduction type polarization plate.

A plurality of metal fine lines g are arranged without intersecting witheach other. A space between the adjacent metal fine lines g is atransmission region d through which the entire or a part of the sourcelight 71 can be transmitted. In a case where the width of the metal fineline g and an interval between the adjacent metal fine lines g, that is,the width of the metal fine line g and the width of the transmissionregion d, are sufficiently smaller than the wavelength of the sourcelight 71 of the generator 41, the optical scale 11 can performpolarization separation with respect to the incident light 73 of thesource light 71. For this reason, the optical scale 11 includespolarizers of which the polarization directions Pm in the plane areuniform. In a circumferential direction where the optical scale 11 isrotated, the polarization axis of the incident light 73 incident on thedetector 35 is changed in accordance with the rotation of the opticalscale 11. In this embodiment, the polarization axis is changed byrepeating an increase and a decrease with respect to one rotation of theoptical scale 11 two times.

It is not necessary for the optical scale 11 to make segments havingdifferent polarization directions minute. Then, the optical scale 11 hasthe uniform polarization direction Pm, and thus, the optical scale 11has no boundary between regions having different polarization directionsPm. This configuration suppresses a disturbance in a polarization stateof the incident light 73, which would be caused due to a boundary. Theoptical encoder 2 of this embodiment is capable of reducing aprobability that erroneous detection or a noise occurs.

FIG. 18 is an explanatory diagram for illustrating an example of thefirst light receiver PD1 of the detector 35. FIG. 19 is an explanatorydiagram for illustrating an example of the third light receiver PD3 ofthe detector 35. The generator 41 is a light emitting diode, forexample. As illustrated in FIG. 3, the source light 71 emitted from thegenerator 41 is transmitted through the optical scale 11, and thentransmitted through the polarization layer PP1, the polarization layerPP2, the polarization layer PP3, and the polarization layer PP4, as theincident light 73 to be incident on the first light receiver PD1, thesecond light receiver PD2, the third light receiver PD3, and the fourthlight receiver PD4, respectively. In the plan view from the z axisdirection, the first light receiver PD1, the second light receiver PD2,the third light receiver PD3, and the fourth light receiver PD4 arearranged around the generator 41. Distances from the first lightreceiver PD1, the second light receiver PD2, the third light receiverPD3, and the fourth light receiver PD4 to the arrangement center S0 areequal to each other. This structure reduces a calculation load of theCPU 4 c functioning as an arithmetic unit.

As illustrated in FIG. 18, the first light receiver PD1 includes asilicon substrate 34, a light receiver 37, and a first polarizationlayer 39 a. As illustrated in FIG. 19, the third light receiver PD3includes the silicon substrate 34, the light receiver 37, and a secondpolarization layer 39 b. For example, the silicon substrate 34 is ann-type semiconductor, and the light receiver 37 is a p-typesemiconductor. Thus, the silicon substrate 34 and the light receiver 37can constitute a P-N junction photodiode. The first polarization layer39 a and the second polarization layer 39 b each can be formed of aphotoinduction type polarization layer, a wire grid pattern in whichmetal fine lines are arranged parallel to each other, or the like. Thefirst polarization layer 39 a separates a light component in a firstpolarization direction from the incident light 73 that is incident onthe optical scale 11 illustrated in FIG. 3 from the source light 71. Thesecond polarization layer 39 b separates a light component in a secondpolarization direction from the incident light 73. It is preferred thata polarization axis of the first separated light and a polarization axisof the second separated light be relatively different by 90°. Thisconfiguration allows the CPU 4 c of the arithmetic device 3 to calculatethe polarization angle easily.

Similarly, describing by using FIG. 18 and FIG. 19, the second lightreceiver PD2 includes the silicon substrate 34, the light receiver 37,and the first polarization layer 39 a. As illustrated in FIG. 19, thefourth light receiver PD4 includes the silicon substrate 34, the lightreceiver 37, and the second polarization layer 39 b. For example, thesilicon substrate 34 is an n-type semiconductor, and the light receiver37 is a p-type semiconductor. Thus, the silicon substrate 34 and thelight receiver 37 constitute a P-N junction photodiode. The firstpolarization layer 39 a and the second polarization layer 39 b each canbe formed of a photoinduction polarization layer, a wire grid pattern inwhich metal fine lines are arranged parallel to each other, or the like.The first polarization layer 39 a separates a light component in thefirst polarization direction from the incident light 73 that is incidenton the optical scale 11 illustrated in FIG. 3 from the source light 71.The second polarization layer 39 b separates a light component in thesecond polarization direction from the incident light 73. It ispreferred that the polarization axis of the first separated light andthe polarization axis of the second separated light be relativelydifferent by 90°. This configuration allows the CPU 4 c of thearithmetic device 3 to calculate the polarization angle easily.

The first light receiver PD1, the second light receiver PD2, the thirdlight receiver PD3, and the fourth light receiver PD4 receive lightthrough the respective polarization layers PP1, PP2, PP3, and PP4separating light components in different polarization directions fromthe incident light 73. For this reason, it is preferred that thepolarization axis of the separation of the polarization layer PP1 andthe polarization axis of the separation of the polarization layer PP2 berelatively different by 45°. It is preferred that the polarization axisof the separation of the polarization layer PP2 and the polarizationaxis of the separation of the polarization layer PP3 be relativelydifferent by 45°. It is preferred that the polarization axis of theseparation of the polarization layer PP3 and the polarization axis ofthe separation of the polarization layer PP4 be relatively different by45°. It is preferred that the polarization axis of the separation of thepolarization layer PP4 and the polarization axis of the separation ofthe polarization layer PP1 be relatively different by 45°. Thisconfiguration allows the CPU 4 c of the arithmetic device 3 to calculatethe polarization angle easily.

FIG. 20, FIG. 21, and FIG. 22 are explanatory diagrams for illustratingseparation of the polarization component of the optical scale 11. Asillustrated in FIG. 20, incident light polarized in the polarizationdirection Pm by the signal track T1 of the optical scale 11 is received.In FIG. 20, there are a foreign substance D1 and a foreign substance D2in a sensing region. The polarization direction Pm of the incident lightcan be represented by a light intensity PI(−) of a component in thefirst polarization direction and a light intensity PI(+) of a componentin the second polarization direction. As described above, it ispreferred that the first polarization direction and the secondpolarization direction be directions different by 90°, and the firstpolarization direction and the second polarization direction are, forexample, a +45° component and a −45° component with respect to areference direction. In FIG. 20, FIG. 21, and FIG. 22, it is illustratedthat an axis direction of a wire grid is parallel to the paper plane. Ina case where the optical scale 11 is inclined at the same angle withrespect to the paper plane, but the inclination angle is small, thepolarization separation function is not affected. That is, the opticalscale 11 functions as a polarization separation element even in the caseof being inclined with respect to a rotation axis.

As illustrated in FIG. 21, the first light receiver PD1 performs sensingthrough the first polarization layer 39 a separating a component in thefirst polarization direction from the incident light, and thus, sensesthe light intensity PI(−) of the component in the first polarizationdirection. As illustrated in FIG. 22, the third light receiver PD3performs sensing through the second polarization layer 39 b separating acomponent in the second polarization direction from the incident light,and thus, senses the light intensity PI(+) of the component in thesecond polarization direction. Similarly, as illustrated in FIG. 21, thesecond light receiver PD2 performs sensing through the firstpolarization layer 39 a separating a component in the first polarizationdirection from the incident light, and thus, senses the light intensityPI(−) of the component in the first polarization direction. Asillustrated in FIG. 22, the fourth light receiver PD4 performs sensingthrough the second polarization layer 39 b separating a component in thesecond polarization direction from the incident light, and thus, sensesthe light intensity PI(+) of the component in the second polarizationdirection.

FIG. 23 is a functional block diagram of the optical encoder 2. FIG. 24is an explanatory diagram for illustrating the rotation angle of theoptical scale 11 and a light intensity change of the polarizationcomponent of each of the light receivers. As illustrated in FIG. 23, thegenerator 41 emits light based on a reference signal and irradiates theoptical scale 11 with the source light 71. The incident light 73 that isthe transmitted light is received by the detector 35. The differentialoperational circuit DS performs differential operational processingusing the detection signal that is output from the detector 35 and isamplified by the pre-amplifier AMP. The pre-amplifier AMP can be omittedaccording to the size of the output of the detector 35.

The differential operational circuit DS acquires the light intensityPI(−) of the component (the first separated light) in the firstpolarization direction, and the light intensity PI(+) of the component(the second separated light) in the second polarization direction, whichare the detection signals of the detector 35. The outputs of the firstlight receiver PD1, the second light receiver PD2, the third lightreceiver PD3, and the fourth light receiver PD4, corresponding to thelight intensity PI(−) and the light intensity PI(+), are, for example,light intensities I1, I2, I3, and I4 of which the phase is shifted inaccordance with the rotation of the optical scale 11 as illustrated inFIG. 24.

The differential operational circuit DS calculates a differential signalVc and a differential signal Vs, which depend on the rotation of theoptical scale 11, from the light intensity PI(−) of the component in thefirst polarization direction and the light intensity PI(+) of thecomponent in the second polarization direction, according to Expression(1) and Expression (2). The differential signal Vc is a signalcorresponding to a so-called cosine (cos) component, and thedifferential signal Vs is a signal corresponding to a so-called sine(sin) component.Vc=(I1−I3)/(I1+I3)  (1)Vs=(I2−I4)/(I2+I4)  (2)

Thus, the differential operational circuit DS calculates the sum [I1+I3]of light intensities and a difference [I1−I3] between the lightintensities on the basis of the light intensity I1 and the lightintensity 13, and then calculates the differential signal Vc by dividingthe difference [I1−I3] between the light intensities by the sum [I1+I3]of the light intensities. The differential operational circuit DScalculates the sum [I2+I4] of the light intensities and a difference[I2−I4] between the light intensities on the basis of the lightintensity 12 and the light intensity 14, and then calculates thedifferential signal Vs by dividing the difference [I2−I4] between thelight intensities by the sum [I2+I4] of the light intensities. Aparameter affected by the light intensity of the source light 71 is notincluded in the differential signals Vc and Vs calculated by Expression(1) and Expression (2), and thus, the output of the sensor 31 can reducethe influence of the distance between the detector 35 and the opticalscale 11, variations in the light intensity of the generator 41, or thelike. The differential signals Vc and Vs are a function of a rotationangle β of the polarization axis of the optical scale 11 (hereinafter,referred to as a polarization angle), which is the rotation angle of theoptical scale 11. However, in a case where auto power control (APC) ofcontrolling a light amount of a light source provided in the generator41 to be constant is provided, the division described above is notnecessary.

As illustrated in FIG. 23, the differential signals Vc and Vs are inputto the filter circuit NR, and the noise is eliminated. Next, themultiplication circuit AP calculates a Lissajous pattern illustrated inFIG. 25 from the differential signals Vc and Vs to specify the absoluteangle of the rotation angle of the rotor 10 rotated from the initialposition. The differential signals Vc and Vs are differential signals ofwhich the phase is shifted by λ/4, and thus, a Lissajous pattern inwhich a cosine curve of the differential signal Vc is set to ahorizontal axis, and a sine curve of the differential signal Vs is setto a vertical axis, is calculated, and a Lissajous angle is determinedin accordance with the rotation angle. For example, in a case whererotor 10 is rotated once, the Lissajous pattern illustrated in FIG. 25makes two circles. The arithmetic device 3 has a function of storingwhether a rotation position of the optical scale 11 is in a range ofgreater than or equal to 0° and less than 180° or in a range of greaterthan or equal to 180° and less than 360°. Accordingly, the opticalencoder 2 can be an absolute encoder capable of calculating the absoluteposition of the rotor 10.

FIG. 26 is a diagram for illustrating the generator 41. The generator 41illustrated in FIG. 26 is, for example, a light emitting elementpackaged with the light emitting device 41U such as a light emittingdiode. The light emitting device 41U may have other configurations.Specifically, for example, the light emitting device 41U may be a laserlight source such as a vertical resonator surface-emitting laser, afilament, or the like. The generator 41 includes a base substrate 41F, athrough conductive layer 41H embedded in a through hole SH, an externalelectrode 41P electrically connected to the through conductive layer41H, the light emitting device 41U mounted on the base substrate 41F, abonding wire 41 W conductively connecting the light emitting device 41Uand the through conductive layer 41H together, a sealing resin 41Mprotecting the light emitting device 41U, and a light shielding film41R.

The light shielding film 41R of the generator 41 has a function as adiaphragm for the source light 71, in which the source light 71 emittedfrom the light emitting device 41U is directed to a region of anemitting surface 41T. The emitting surface 41T does not include a lenssurface, and a light distribution of the source light 71 represents alight distribution of a predetermined angle 2θo with respect to asectional surface of the emitting surface 41T. The angle 2θo of thelight distribution depends on the generator 41. The angle 20 o is, forexample, 30°, but can be set to an angle greater or less than 30°.

The sensor 31 can be configured using the generator 41 not provided witha lens. Reducing the distance D between the emitting point 41S of thelight generated by the generator 41 and the arrangement center S0 (thedetector 35) improves an SN ratio. The distance W to each of the firstlight receiver PD1, the second light receiver PD2, the third lightreceiver PD3, and the fourth light receiver PD4 can be arranged in aregion where the influence of the diffused light of the generator 41 isreduced and light can be received. For this reason, measurement accuracyof the sensor 31 and the optical encoder 2 is improved. It is alsopossible to use the generator 41 provided with a lens.

FIG. 27 is a diagram illustrating an example of a relationship betweenan emitting region of the light from the generator 41 and the positionsof the detector 35 and the shaft 12. In this embodiment, the detectiontarget that is generated by the generator 41 and is detected by thedetector 35, is light. An emitting angle (the angle 20 o describedabove) of the source light 71 of the generator 41 can be arbitrarily setin accordance with the design. Accordingly, as illustrated in FIG. 27,while all of the light receiving regions of the detector 35 are includedin the region corresponding to the emitting angle of the source light71, it is possible not to include the connection portion 53 and theshaft 12 therein. However, it is difficult to keep the source light 71emitted from the light emitting diode as a light source completelywithin the emitting region to make light leakage be zero. In addition,in consideration of the reflected light after emitting, or the like, itis difficult to completely prevent the light other than the directsource light 71 (for example, irregularly reflected light or the like)from being incident on the detector 35. Therefore, in this embodiment,in order to reduce the reflected light, the surface of the substrate 50on which the light emitting element and the light receiving elements areprovided, is subjected to a light antireflection treatment.Specifically, of the plate surfaces of the substrate 50, a coatingtreatment of coating at least the surface (the front surface 50A) on aside where the generator 41 and the detector 35 are provided with anantireflection material having light absorbing properties, such as ablack coating material, can be adopted as the light antireflectiontreatment.

In consideration of a possibility that light is reflected on the outercircumferential surface of the shaft 12, the shaft 12 may be subjectedto the antireflection treatment. In this case, the sensor 31 includes ascale (the optical scale 11) and a rotation support portion (the body 21of the stator 20) and is subjected to the light antireflectiontreatment. The scale affects light by being rotatably moved in thedetection region that is the space between the generator 41 and thedetector 35, and the rotation support portion includes the shaft 12 thatrotatably supports the scale. Specifically, for example, the outercircumferential surface of the metal shaft 12 can be subjected to aplating treatment using a black oxide film, the above-mentioned coatingtreatment, or the like, as the light antireflection treatment. With asimilar idea, the inner circumferential surface of the stator 20containing the optical scale 11 and the substrate 50 may be subjected tothe antireflection treatment.

Next, a manufacturing method of the sensor 31 will be described withreference to a flowchart of FIG. 28. FIG. 28 is a flowchart of anexemplary process of manufacturing the sensor 31. Hereinafter, anoperation process mainly performed by a manufacturing operator or amanufacturing machine operated by the manufacturing operator will bedescribed. First, the substrate 50, in which the first portion 51 to beprovided with the generator 41 is integrated with the second portion 52to be provided with the detector 35, is formed (Step S1). Specifically,for example, as illustrated in FIG. 14, the FPC, which includes thesemicircular arc-like first portion 51, the circular second portion 52,the connection portion 53 connecting the first portion 51 and the secondportion 52 together, the harness portion 54 extending from the firstportion 51 to a side opposite to the connection portion 53, and the bentportions 55 a and 55 b for bending the substrate 50, is formed. In thisstep, the signal line, the power line, the ground pattern 80, and thelike, to be connected to various circuits to be mounted on the substrate50 in the subsequent steps, are formed on the FPC. Here, for example, asillustrated in FIG. 9, in the ground pattern 80, the ground pattern 81of the bent portion 55 a and the ground pattern 82 of the bent portion55 b are formed to be narrower than at least the ground pattern 83 ofthe first portion 51 and the ground pattern 84 of the second portion 52.Thus, the manufacturing method of the sensor 31 (the optical sensor)according to this embodiment includes a step of preparing the substrate50 including the first portion 51 to be provided with the generator 41,the second portion 52 to be provided with the detector 35, the bentportions 55 a and 55 b to be bent between the first portion 51 and thesecond portion 52 such that the generator 41 and the detector 35 faceeach other, and the ground pattern 80 provided in the portion includingthe first portion 51, the second portion 52, and the bent portions 55 aand 55 b. The front surface of the FPC is subjected to theantireflection treatment. At this time, the terminal portion to whichthe wiring of various circuits including the generator 41 and thedetector 35 is to be connected later, is not subjected to theantireflection treatment.

Next, various components are attached to the substrate 50. Specifically,for example, first, the support substrate 65 is attached to the rearsurface 51B of the first portion 51 (Step S2). Next, various steps forproviding the IC circuit 60 on the rear surface 52B of the secondportion 52 are performed. More specifically, solder printing formounting the IC circuit 60 on the rear surface 52B of the second portion52 (Step S3), mounting the IC circuit 60 on the rear surface 52B of thesecond portion 52 (Step S4), reflow by heating the rear surface 52B ofthe second portion 52 after being subjected to the mounting at Step S4(Step S5), a visual examination of the soldering of the rear surface 52Bof the second portion 52 (Step S6), and the like, are performed, andthus, the IC circuit 60 is provided on the rear surface 52B of thesecond portion 52. Thus, the manufacturing method of the sensor 31 (theoptical sensor) according to this embodiment includes a step ofattaching the plate-like support member (the IC circuit 60 and thesupport substrate 65) for keeping a surface (the front surfaces 51A and52A) on which an electronic component is provided flat, to the surface(the rear surfaces 51B and 52B) on the rear side of each of the surface(the front surface 51A) of the first portion 51 on which an electroniccomponent including the generator 41 is provided and the surface (thefront surface 52A) of the second portion 52 on which an electroniccomponent including the detector 35 is provided.

Next, various steps for attaching the component to the front surface 50Aof the substrate 50 are performed. More specifically, solder printingfor mounting the generator 41 and a part of the component 61 on thefront surface 51A of the first portion 51, and for mounting the detector35 on the front surface 52A of the second portion 52 (Step S7), mountingvarious circuits including the generator 41 and the detector 35 on thefront surface 50A (Step S8), reflow by heating the front surface 50Aafter being subjected to the mounting at Step S8 (Step S9), a visualexamination of the soldering of the front surface 50A (Step S10), andthe like, are performed, and thus, a component that is subjected towiring connection by soldering is attached to the front surface 50A.After that, the substrate 50 is washed (Step S11). After the substrate50 is washed, a paste (for example, an Ag paste) for attachment of thebare chip as a part of the component 61 is applied onto the frontsurface 50A (Step S12), the bare chip is mounted (Step S13), and thebare chip is fixed by thermal curing (Step S14). Then, the bare chip andthe wiring of the substrate 50 are connected together by wire bonding(Step S15). After the wire bonding, the front surface 50A of thesubstrate 50 is coated with a resin that is cured by an ultraviolet ray(a UV curable resin) (Step S16), a sealing substrate (for example, aglass substrate) is mounted on the front surface 50A coated with the UVcurable resin (Step S17), and a UV curing treatment of curing the UVcurable resin by applying an ultraviolet ray thereto is performed (StepS18). Thus, the manufacturing method of the sensor 31 (the opticalsensor) according to this embodiment includes a step of providing thegenerator 41 on the first portion 51 and of providing the detector 35 onthe second portion 52. Here, in a case where the surface (the rearsurface 50B) of the substrate 50 on a side where the plate-like member(for example, the support substrate 65) is provided is defined as onesurface, the generator 41 and the detector 35 are provided on the othersurface (the front surface 50A). One or more electronic components (forexample, the detector 35 and the component 61) provided on the frontsurface 52A of the second portion 52 are arranged within a regioncorresponding to a region in the rear surface 52B where the package ofthe IC circuit 60 is arranged.

The wire bonding is, for example, Au wire bonding using a gold wire, butthe Au wire bonding is merely an example, the wire bonding is notlimited thereto, and can be changed as appropriate. Instead of the wirebonding, tape automated bonding (TAB) may be used, or the wiring of thesubstrate may be soldered with the bare chip as a flip chip.

Next, the generator 41 and the detector 35 are made to face each other.Specifically, for example, the substrate 50 is bent in the bent portions55 a and 55 b such that the surface of the first portion 51, on whichthe generator 41 is provided (the front surface 51A), and the surface ofthe second portion 52, on which the detector 35 is provided (the frontsurface 52A), are parallel to each other and face each other (Step S19).Thus, the manufacturing method of the sensor 31 (the optical sensor)according to this embodiment includes a step of bending the substrate50, which is a flexible substrate (FPC), in the bent portions 55 a and55 b such that the surface (the front surface 51A) of the first portion51, on which the generator 41 is provided, and the surface (the frontsurface 52A) of the second portion 52, on which the detector 35 isprovided, face each other.

As exemplified in the steps of Steps S7 to S14 described above, themanufacturing method of the sensor 31 (the optical sensor) according tothis embodiment includes a step of providing the generator 41 on thefirst portion 51 and of providing the detector 35 on the second portion52. It is preferred that the first light receiver PD1 to the fourthlight receiver PD4 included in the detector 35 be arranged in differentpositions on a predetermined plane (for example, the front surface 52A),that the distances (the distances W) from the four light receivingelements to one point on the predetermined plane be equal to each other,and that the four line segments connecting one point and the centers ofthe light receiving regions of the four light receiving elements formright angles to each other. Further, it is preferred that, with thesubstrate 50 bent, the straight line L2 that is the normal line of apredetermined plane (the front surface 52A) passing through one point(the arrangement center S0), pass through the center of the emittingpoint 41S of the light generated by the generator 41. It is preferredthat the generator 41 and the detector 35 be provided in considerationof such a condition. Specifically, the configuration satisfies a firstcondition in which the first axis LA serving as the bending axis of thebent portion 55 a is parallel to the second axis LB serving as thebending axis of the bent portion 55 b. The configuration satisfies asecond condition in which, on the plane before the substrate 50 is bent,the distance (the distance W1) between the first axis LA and the firstpoint (for example, the emitting point 41S) that is the generationcenter point of the detection target of the generator 41, is equal tothe distance (the distance W2) between the second axis LB and the secondpoint (for example, the arrangement center S0) that is either the centerof the detection region of the detection target of the detector 35 orthe arrangement center of the plurality of detection regions of thedetector 35. The configuration satisfies a third condition in which thefirst point and the second point are arranged on the same straight line(for example, the straight line L1), which intersects with (orthree-dimensionally intersects with) the first axis LA and the secondaxis LB at a right angle in the substrate 50 before being bent. Thewiring of the generator 41 and the detector 35 is provided in formingthe substrate 50, the first axis LA and the second axis LB aredetermined, and the arrangement of the generator 41 and the detector 35when they are mounted is determined, such that the first condition, thesecond condition, and the third condition are satisfied.

Next, the housing (for example, the stator 20) is formed (Step S20).Specifically, the housing including the first member (for example, thechassis 22) to which a part of the substrate 50 is fixed and the secondmember (for example, the body 21) movably supporting a member (forexample, the optical scale 11), is formed. The member (for example, theoptical scale 11) affects light by being moved in the detection regionthat is the space between the generator 41 and the detector 35. In thisembodiment, the cover 23 is further formed as one configuration of thestator 20 that is the housing containing the substrate 50 and theoptical scale 11, but such a configuration is merely an example of aspecific configuration of the housing, and is not limited thereto. Forexample, the cover 23 may be integrated with the chassis 22. The shaft12 provided in the body 21 that is the second member, may be a shaft ofwhich the outer circumferential surface is subjected to theantireflection treatment. The inner circumferential surface of thestator 20, which is formed to contain the substrate 50 and the opticalscale 11, may be subjected to the antireflection treatment.

After that, a step relevant to the assembly of the sensor 31 (Step S21)is performed. Hereinafter, the step relevant to the assembly in themanufacturing of the sensor 31 will be described. In the manufacturingof the sensor 31, the substrate 50 and the motion body (for example, theoptical scale 11) are relatively moved such that the motion body entersthe region between the generator 41 and the detector 35 (the detectionregion). Specifically, in the manufacturing of the sensor 31, forexample, as illustrated in FIG. 15 and FIG. 16, the substrate 50 and themotion body are relatively moved such that the motion body enters theregion (the detection region) from a side opposite to the connectionportion 53. In the substrate 50, the connection portion 53 is positionedon a side opposite to the harness portion 54 with the second portion 52therebetween, and thus, in this embodiment, the substrate 50 and themotion body are relatively moved such that the motion body enters thedetection region from the harness portion 54 side.

More specifically, with respect to a predetermined plane (for example,the front surface 52A of the second portion 52), the plate surfaces ofthe first portion 51, the second portion 52, and the optical scale 11 ofthe bent substrate 50 are made to be along the predetermined plane. Inthis state, at least one of the substrate 50 and the stator 20 includingthe optical scale 11 is moved in the direction along the predeterminedplane, and thus, the optical scale 11 is provided in the detectionregion. For example, in a position where the optical scale 11 isprovided, in a columnar outer circumferential surface of the stator 20,the opening portion (for example, the opening portion 21 a) into whichthe substrate 50 can be inserted in the direction along the platesurface of the optical scale 11, is provided. The substrate 50 is madeto enter the opening portion, and thus, the optical scale 11 is providedin the detection region. In this case, the substrate 50 enters theopening portion 21 a by being inserted from the harness portion 54 side.Further, the semicircular arc-like first portion 51 enters a side of theoptical scale 11 where the shaft 12 is located, and the circular secondportion 52 enters a side of the optical scale 11 where the shaft 12 isnot located.

In this embodiment, the first portion 51 and the second portion 52 areparallel to each other. Consequently, in the manufacturing method of thesensor 31 according to this embodiment, which includes a step of,assuming that the front surface 52A of the second portion 52 is apredetermined plane, moving at least any one of the substrate 50 and thestator 20 including the optical scale 11 in the direction along thepredetermined plane, a relative movement direction of the substrate 50and the motion body is along the first portion 51 and the second portion52.

The step relevant to the assembly in the manufacturing of the sensor 31will be described below by using an actual example. First, the substrate50 is attached to the first member (the chassis 22) that is one of aplurality of members included in the housing (the stator 20) of thesensor 31. After that, the housing is assembled by bringing the firstmember closer to the second member (the body 21) that is one of theplurality of members included in the housing and supports the motionbody, and the substrate 50 and the motion body are relatively moved suchthat the motion body enters the region between the generator 41 and thedetector 35. Specifically, as illustrated in FIG. 11, the second portion52 of the substrate 50 is fixed to the chassis 22. Then, as illustratedin FIG. 15, the chassis 22 to which the second portion 52 is fixed, andthe body 21 in which the rotor 10 is rotatably provided, are provided soas to have a position relationship where the first portion 51 and thesecond portion 52, and the optical scale 11 are substantially parallelto each other, and where the optical scale 11 is positioned in thedetection region between the first portion 51 and the second portion 52.That is, the chassis 22 and the body 21 are provided so as to have aposition relationship where the first portion 51 and the second portion52, and the optical scale 11 are aligned in a predetermined plane. Insuch a position relationship, the body 21 and the chassis 22 are broughtcloser to each other along the predetermined plane such that the chassis22 enters the body 21 from the opening portion 21 a of the body 21, andthen the body 21 and the chassis 22 are made to abut on each other.Thus, the body 21 and the chassis 22 are assembled. Consequently, theoptical scale 11 is provided in the detection region. Here, in bringingthe body 21 closer to the chassis 22 in the position relationship wherethe optical scale 11 is positioned in the detection region between thefirst portion 51 and the second portion 52, it is preferred that thesupport substrate 65 adhering to the rear surface 51B of the firstportion 51 be kept from abutting on the adhesive surface 21 c of thebody 21. Then, in a step where the body 21 and the chassis 22 areassembled by causing the body 21 to abut on the chassis 22, the chassis22 is pushed up such that the chassis 22 becomes closer to the adhesivesurface 21 c, and thus, the support substrate 65 and the adhesivesurface 21 c abut on each other and adhere to each other. According tosuch an assembly method, in a state where one surface of the plate-likemember (the support substrate 65) adheres to the surface (for example,the rear surface 51B) of the other (for example, the first portion 51)on a side opposite to a side facing the detection region, the othersurface of the plate-like member adheres to the second member (forexample, the body 21). It is preferred that various specific designmatters such as the length of the connection portion 53, an extensionlength of the shaft 12 on the adhesive surface 21 c side, and thethickness of the support substrate 65, be set such that the body 21 andthe chassis 22 can be assembled.

The cut-out portion 51 a keeps the shaft 12 from being in contact withthe substrate 50 even after the body 21 and the chassis 22 areassembled. This configuration inhibits contact between the shaft 12 andsubstrate 50 and prevents the rotation of the shaft 12 from beinghindered. Thus, in the manufacturing method of the sensor 31 accordingto this embodiment, a cutout (the cut-out portion 51 a) for causing theshaft 12 and the substrate 50 to be in a non-contact state, in a statewhere the motion body enters the region between the generator 41 and thedetector 35, is provided in the first portion 51.

The body 21 and the chassis 22 are assembled, and then, the harnessportion 54 extends from the cut-out portion 21 b provided on a sideopposite to the opening portion 21 a of the body 21. After that, in acase where the cover 23 is separated from the chassis 22, the cover 23is attached to the body 21 so as to cover the opening portion 21 a ofthe body 21. That is, in the manufacturing method of the sensor 31according to this embodiment, the first member (the chassis 22) and thesecond member (the body 21) are assembled, and then, an entrance (theopening portion 21 a) in the second member through which the substrate50 enters is covered with a covering member (the cover 23). In FIG. 14to FIG. 17, the illustration of a part of the circuits such as thedetector 35 is omitted, but in fact, various circuits including thedetector 35 have been mounted.

In a case where the connector CNT is mounted in advance on the substrate50, for example, in a positioning step of the body 21 and the chassis 22before the body 21 and the chassis 22 are relatively moved, the body 21and the chassis 22 may have a position relationship where the tip endside of the harness portion 54 is exposed to the outside the body 21.Thus, when the body 21 and the chassis 22 are relatively moved such thatthe motion body enters the region between the generator 41 and thedetector 35, the connector CNT is prevented from being caught at thecut-out portion 21 b without passing therethrough, and thus excellentassembly is performed. The connector CNT may be provided in thesubstrate 50 before the housing (the stator 20) is assembled. Theconnector CNT may be provided after the housing is assembled.

Thus, the housing of the sensor 31 includes the first member (thechassis 22) to which the substrate 50 is attached and the second member(the body 21) in which the motion body is provided. The second memberand the first member are relatively moved along a predetermineddirection and abut on each other, and thus, the housing is assembled.The predetermined direction is a direction in which the motion body canenter the region (the detection region) between the generator 41 and thedetector 35.

As described above, according to this embodiment, the substrate 50includes the first portion 51 on which the generator 41 is provided andthe second portion 52 on which the detector 35 is provided, therebyenabling to position the generator 41 and the detector 35 by a simpleoperation such as bending the substrate 50. Thus, according to thisembodiment, the positioning between the generator 41 and the detector 35is more easily performed. Such positioning can be easily performed,thereby enabling to simplify a manufacturing step relevant to thepositioning. Therefore, according to this embodiment, the sensor is moreeasily manufactured. In the ground pattern 80, the ground patterns 81and 82 of the bent portions are narrower than the ground pattern 83 ofthe first portion 51, the ground pattern 84 of the second portion 52,and the ground pattern 85 of the connection portion 53. Thus, thisconfiguration allows the bent portions 55 a and 55 b to be bent moreeasily than other portions, with respect to a condition such as theelasticity and the rigidity of the substrate 50. Consequently, thesensor can be manufactured more easily.

Further, providing the connection portion 53 makes it easier to providethe space between the first portion 51 and the second portion 52. Thismakes it easier to provide the detection region between the generator 41and the detector 35.

The substrate 50 and the motion body are relatively moved such that themotion body enters the region between the generator 41 and the detector35, thereby enabling to manufacture the sensor 31 capable of sensing themotion of the motion body with the generator 41 and the detector 35provided on the substrate 50 in which the first portion 51 and thesecond portion 52 are integrated. The motion body enters the region (thedetection region) from a side opposite to the connection portion 53,thereby making the ease of positioning and manufacturing and the meritof providing the connection portion 53 compatible.

The first portion 51 and the second portion 52 are provided parallel toeach other, and thus, a position relationship between the generator 41provided on the first portion 51, and the detector 35 provided on thesecond portion 52 can be adjusted on the basis of a relationship betweenthe first portion 51 and the second portion 52 provided parallel to eachother. This facilitates position adjustment for allowing the detector 35to be arranged in a generation region of the detection target generatedby the generator 41 when the generator 41 has directive properties, andthe design relevant to the position angle when the generator 41 and thedetector 35 are provided on the substrate 50. A relative movementdirection between the substrate 50 and the motion body is along thefirst portion 51 and the second portion 52. This makes it easier todetermine the reference of the relative movement direction and makes itdifficult for the substrate 50 and the motion body to be in contact witheach other when they are relatively moved. Consequently, the motion bodycan more easily enter the region (the detection region).

A cutout (for example, the cut-out portion 51 a) for setting the shaft12 and the substrate 50 to be in a non-contact state, in a state wherethe motion body enters the region between the generator 41 and thedetector 35, is provided. Thus, the cutout inhibits contact between thesubstrate 50 and the shaft 12 and prevents the motion of the shaft 12from being hindered.

The first member (for example, the chassis 22) and the second member(for example, the body 21) are brought closer to each other to assemblethe housing, and the substrate 50 and the motion body are relativelymoved such that the motion body enters the region between the generator41 and the detector 35, thereby allowing the motion body to enter theregion between the generator 41 and the detector 35 in one step of theassembly of the housing, simultaneously with the assembly. Theadjustment of a position relationship between the motion body andradiation from the generator 41 to the detector 35 can also be set inaccordance with the position relationship between the first member andthe second member in the assembly of the housing. Therefore, accordingto the sensor 31 of this embodiment, the manufacturing is more easilyperformed.

The first member and the second member are assembled, and then, theentrance (for example, the opening portion 21 a) of the second memberthrough which the substrate enters is covered with the covering member(for example, the cover 23), thereby sealing the generator 41, thedetector 35, and the motion body, in the housing. Therefore, accordingto this embodiment, the sensor 31 is capable of sensing the motion ofthe motion body with high accuracy.

The connection portion 53 is provided with the wiring connected to thegenerator 41, thereby enabling to integrate the wiring connected to thegenerator 41 with the connection portion 53. This makes the connectionportion 53 and the substrate 50 including the wiring more compact.

The width of the connection portion 53 is less than those of the firstportion 51 and the second portion 52. This configuration makes the areaof the substrate 50 smaller, compared to a case where the width of thesubstrate 50 including the first portion 51 and the second portion 52with connection portion 53 therebetween is uniform, thereby furtherreducing the weight of the substrate 50.

The substrate 50 is bent at two portions, thereby enabling to providethe detection region between the generator 41 and the detector 35 bybending the substrate 50. The bending portion is therefore clarified.

The first portion 51 is smaller than the second portion 52, therebyfurther reducing the weight of the first portion 51. This makes therequirements for the connection portion 53, such as strength, relax.

The substrate 50 is bent into a shape (for example, a U-shape) where thegenerator 41 and the detector 35 face each other, and thus, a part ofthe substrate 50 (for example, the second portion 52 or the like) can bealong the plane in the stator 20 (for example, the plane portion of thechassis 22, or the like), and the handling in providing the sensor 31 inthe housing is more easily performed.

The substrate 50 is a flexible substrate. This makes it easier toperform a series of operations in which the component including thegenerator 41 and the detector 35 is mounted on the substrate 50 in astate where the first portion 51 and the second portion 52 exist in thesame plane, and then, the substrate 50 is processed such that thedetection region is provided between the generator 41 and the detector35.

The substrate 50 includes the harness portion 54 including the wiringconnected to the generator 41 and the detector 35. Thus, the wiringconnected to the configuration of the sensor 31 including the generator41 and the detector 35 can be collectively provided in the substrate 50.That is, by providing the harness portion 54, it is not necessary toseparately pull out the wiring from a component (the circuit or thelike) requiring the wiring. For this reason, it is not necessary toseparately handle the substrate 50 and the wiring, which makes it easierto handle the sensor 31.

The detector 35 detects changes in the detection target, which occursdue to changes in the physical amount of the detection region, and thus,a target causing changes in the physical amount can be set to be asensing target of the sensor 31.

The detection target is the electromagnetic wave (for example, the lightemitted from the generator 41), thereby enabling to detect changes inthe detection region due to changes in the electromagnetic wave.

A change in the physical amount is caused by the rotation of the motionbody (for example, the optical scale 11) existing in the detectionregion, and thus, a rotation motion of the motion body can be thesensing target of the sensor 31.

One (for example, the second portion 52) of the first portion 51 and thesecond portion 52 is fixed to the first member (for example, the chassis22), and the surface of the other (for example, the first portion 51) ona side opposite to a side facing the detection region adheres to thesecond member (for example, the body 21). That is, in the assembly ofthe sensor 31, it is sufficient that the one is fixed to the firstmember, and the surface of the other on a side opposite to a side facingthe detection region adheres to the second member, and thus, theassembly of the sensor 31 is more easily performed.

Only by providing the plate-like member (for example, the supportsubstrate 65) having adhesiveness on both surfaces, the surface of theother on a side opposite to a side facing the detection region adheresto the second member, thereby enabling to assemble the sensor 31 moreeasily.

The plate-like member (for example, the support substrate 65) isattached to the surface of the other on a side opposite to a side facingthe detection region before the housing (for example, the stator 20) isassembled, thereby allowing the surface of the other to adhere to thesecond member in a state where the plate-like member is integrated withthe substrate 50, and therefore, the sensor is assembled more easily.

The four light receiving elements are arranged in different positions ona predetermined plane (for example, the front surface 52A), all of thedistances (the distances W) from the four light receiving elements toone point (the arrangement center S0) on the predetermined plane areequal to each other, four line segments connecting one point and thecenters of the light receiving regions of the four light receivingelements form right angles (01 to 04) to each other, and the normal line(for example, the straight line L2) of the predetermined plane passingthrough the one point passes the emitting point 41S of the lightgenerated by the generator 41. This configuration makes the distances ofthe four light receiving elements from the light emitting element equalto each other, thereby reducing variations in the outputs in accordancewith the sensing of light by the light receiving elements. Thus,according to this embodiment, the outputs of the light receivingelements are more stabilized.

The support member is attached to the surface (for example, the rearsurfaces 51B and 52B) on the rear side of the FPC, the support memberbeing a member for keeping the surface (for example, the front surfaces51A and 52A) on the opposite side thereof flat. This configurationfurther reduces stress on a connection portion between the FPC and theelectronic component provided on the FPC. Thus, a defect according tothe connection portion between the FPC and the electronic componentprovided on the FPC is reduced. Consequently, reliability relevant tothe normal motion of the sensor 31 is increased. Further, the stress onthe connection portion is reduced, thereby reducing the degree ofdifficulty in mounting the electronic component on the FPC, which makesit easier to provide the electronic component on the surface opposite tothe surface on which the support member is provided.

The package of the integrated circuit (for example, the IC circuit 60)provided on the surface on the rear side (for example, the rear surface52B), can be utilized as the support member of the electronic componentprovided on the surface on the opposite side (for example, the frontsurface 52A). Further, the integrated circuit is also one of thecircuits included in the sensor 31. Thus, circuits are provided on bothsurfaces of the FPC, and therefore the substrate area is utilized moreefficiently, thereby facilitating more easily reducing the area of theFPC with respect to the necessary circuit scale. Consequently, thesensor 31 is downsized more easily due to high integration of thecircuit.

As with the support substrate 65, the plate-like member havinginsulating properties, formed corresponding to the shape of the firstportion 51, is provided, and thus, the entire surface (for example, thefront surface 51A) on which the electronic component is provided issupported by the support member.

The surface (for example, the front surface 51A) of the first portion51, on which the generator 41 is provided, and the surface (for example,the front surface 52A) of the second portion 52, on which the detector35 is provided, are provided parallel to each other and face each other.Further, the first axis LA and the second axis LB are parallel to eachother, and the distance W1 between the first point (for example, theemitting point 41S) and the first axis LA, and the distance W2 betweenthe second point (for example, the arrangement center S0) and the secondaxis LB, are equal to each other. Furthermore, the first point and thesecond point exist on the same straight line (for example, the straightline L1) intersecting with (or three-dimensionally intersecting with)the first axis and the second axis at a right angle in the substrate 50before being bent. With this configuration, the first point and thesecond point exist on the same straight line (for example, the straightline L2) orthogonal to the first portion 51 and the second portion 52after the substrate 50 is bent. Consequently, the generator 41 and thedetector 35 are provided facing each other with higher accuracy, therebyfurther stabilizing the output of the detector 35.

The surface of the substrate 50, on which the generator 41 and thedetector 35 are provided (the front surface 50A), is subjected to areflection treatment, thereby reducing the reflection of the lightemitted from the generator 41, on the substrate. This reduces the outputof the detector 35 in accordance with the detection of the reflectedlight, thereby further stabilizing the output of the detector 35.

The shaft 12 is subjected to the antireflection treatment, therebyreducing the reflection of the light emitted from the generator 41, onthe shaft 12. This reduces the output of the detector 35 in accordancewith the detection of the reflected light, thereby further stabilizingthe output of the detector 35.

The sensor 31 functions as a rotary encoder, thereby detecting the angleposition such as the turning angle of the turning motion body that isconnected to the sensor 31.

FIG. 29 is a diagram illustrating another arrangement example of theplurality of light receiving elements of the detector 35. As illustratedin FIG. 29, the detector 35 may be configured such that the first lightreceiver PD1 to the fourth light receiver PD4 respectively including thesquare polarization layers PP1 to PP4 are arranged at four corners of asquare arrangement region 35A, centered around the arrangement centerS0. Even in this case, the four light receiving elements can be arrangedat the same distance from the arrangement center S0, and the four linesegments connecting the arrangement center S0 and the centers of thelight receiving regions of the four light receiving elements can beformed at right angles to each other. The distance between thearrangement center S0 and each of the four light receiving elements isarbitrarily set. However, each of the four light receiving elements candetect the light with the attenuation of the source light 71 from thegenerator 41 becoming less, as the distance is set shorter. The fourlight receiving elements may be separately provided on the secondportion 52. Alternatively, the detector 35 as a package in which aposition relationship between the four light receiving elements and thearrangement center S0 is fixed in advance may be provided on the secondportion 52. By adopting such a package, the arrangement of the fourlight receiving elements is more easily adjusted.

The first portion 51 and the second portion 52 may be other thanparallel to each other. The relationship between the first portion 51and the second portion 52 may be any relationship in which the detectionregion can be provided between the generator 41 and the detector 35, andthe detection target generated by the generator 41 provided in the firstportion 51 can be detected by the detector 35 provided in the secondportion 52. The detailed arrangement between the first portion 51 andthe second portion 52 can be changed as appropriate.

The relationship between the first portion 51 and the second portion 52may be reverse. That is, the first portion 51 may be fixed to the firstmember, and the other surface of the second portion 52 on a sideopposite to a side facing the detection region (the rear surface 52B)may adhere to the second member. However, in this case, for example, thesubstrate 50 and the circuit provided on the substrate 50 (for example,the component 61 or the like) are configured in consideration of theinterference of the housing (for example, the stator 20) with respect tothe configuration, or the like, such as forming the shape of the secondportion 52 to be the same as the shape of first portion 51 in thisembodiment. Further, for example, a cut-out portion such as the cut-outportion 51 a, which prevents the substrate 50 and the shaft 12 frombeing in contact with each other, is provided in accordance with aregion in which the shaft 12 extends. For example, in a case where theshaft 12 extends to penetrate through the optical scale 11 and exists ina position across both of the first portion 51 and the second portion52, the cut-out portion is provided in both of the first portion 51 andthe second portion 52.

The connection portion 53 may not include the wiring. In this case, theconnection portion 53, for example, supports one of the first portion 51and the second portion 52, which is not fixed to the chassis 22. It isnot essential that the one of the first portion 51 and the secondportion 52 be smaller than the other. The first portion 51 and thesecond portion 52 may be the same size, or the one supported by theconnection portion 53 may be larger than the other. The stator 20 or thelike may include a support portion for supporting at least one of theconnection portion 53 and the first portion 51 in this embodiment. Aconfiguration (for example, an adhesive agent, a tape, or a lockingportion such as a protrusion) for fixing at least one of the connectionportion 53 and the first portion 51 in this embodiment to such a supportportion may be provided.

The substrate is not limited to the flexible substrate. The substrate inthe present invention may be any substrate in which the detection regioncan be provided between the generator 41 and the detector 35, thedetection target generated by the generator 41 provided on the firstportion 51 can be detected by the detector 35 provided on the secondportion 52, and the first portion 51 and the second portion 52 areintegrated. For example, a substrate made of a material that can be bentin a portion by heat treatment may be adopted, and the portion (forexample, the connection portion or the like) between the first portionand the second portion may be subjected to such treatment and be bentsuch that the first portion and the second portion face each other. Asubstrate, such as a rigid flexible substrate, including both of aportion hard to be deformed and a portion easily deformed, may beadopted. In this case, the portion hard to be deformed is used for thefirst portion and the second portion, and the portion easily deformed isused for the portion (for example, the connection portion or the like)between the first portion and the second portion, thereby allowing thefirst portion and the second portion to face each other.

The harness portion 54 may be omitted as appropriate. There may be twoor more extension portions functioning as the harness portion. Anextending direction of the extension portion functioning as the harnessportion is arbitrarily set, and there is no particular limitationaccording to the positional relationship with respect to the otherportions of the substrate 50, such as the connection portion 53.

In the relative movement between the motion body and the substrate 50,either one of the motion body or the substrate 50 may be moved to beclose to the other, or both of the motion body and the substrate 50 maybe moved to be close to each other. Specifically, for example, in theassembly of the sensor 31, the first member (the chassis 22) and thesecond member (the body 21) may be brought close to each other in such away that, with either one (for example, the body 21) fixed, the other(for example, the chassis 22) is moved, in such a way that therelationship between the fixing and the movement is reverse, or in sucha way that both of the first member and the second member are moved.

A specific pattern of the signal track T1 of the optical scale 11 andthe pattern of the polarization layers PP1 to PP4 provided in thedetector 35, can be changed as appropriate. Such patterns are determinedin consideration of a relationship between a pattern of a configuration(for example, the optical scale 11) that is provided in the detectionregion and causes polarization, and a pattern of a configuration (forexample, the polarization layer) through which light passes at the timeof performing detection.

The configuration provided in the detection region is not limited to theoptical scale 11 causing the polarization. For example, a plate-likemember provided with a hole or a transmission portion through whichlight selectively passes or is selectively transmitted depending on theturning angle of the rotor 10 may be provided instead of the opticalscale 11. In this case, a change in the turning angle of the rotor 10 isrepresented as a change in a position or a timing at which light isdetected by the detector. Such a detector may not include thepolarization layers PP1 to PP4. A signal indicating the position wherethe light is detected is output from the sensor, and thus, the angleposition of the rotary machine connected to the shaft 12 is detected. Inthis case, it is not necessary that the detector include four lightreceiving elements. For example, one light receiving element may beprovided, or a plurality of light receiving elements may be provided.When there is one light receiving element, it is preferred that adistance between the second axis LB and the center of the detectionregion of the detection target to be detected by the one light receivingelement (the center of the light receiving region) be regarded as thedistance W2 described above, and then, the distance W2 be set to beequal to the distance W1. When there are a plurality of light receivingelements, it is preferred that a distance between the second axis LB andthe arrangement center of the plurality of detection regions of thedetector configured of the plurality of light receiving elements beregarded as the distance W2 described above, and then, the distance W2be set to be equal to the distance W1.

The light emitting element of the generator 41, which emits light, isnot limited to the light emitting diode. The light emitting element maybe a point light source, or may be a surface light source. In a casewhere the light emitting element is the surface light source, the centerof the generation region of the light in the surface light source can beset as a point corresponding to the emitting point 41S of the light inthe embodiment described above, and a straight line that passes throughthe center of the emitting surface of light in the light emittingelement and is along a direction in which the light emitting element andthe light receiving element face each other can be defined. The straightline defined as described above can be regarded as the same straightline as the straight line L2 illustrated in FIG. 13, and the arrangementof each of the four light receiving elements can be determined in thesame manner as that in the embodiment described above. That is, the fourlight receiving elements can be arranged at different positions on apredetermined plane orthogonal to the straight line and at the samedistance from the straight line, and the arrangement of the four lightreceiving elements can be determined such that the four line segments,which connect the respective centers of the light receiving regions ofthe four light receiving elements and an intersection point between thestraight line and a predetermined plane, form at right angles to eachother. The center of the emitting surface 41T may be used instead of theemitting point 41S of the light.

In the embodiment described above, the component (the IC circuit 60 andthe support substrate 65) functioning as the support member for keepingthe surface (the front surfaces 51A and 52A) on which the electroniccomponent is provided flat, is attached to each of the first portion 51and the second portion 52, but it is not necessary that the component beprovided on each of the first portion 51 and the second portion 52. Sucha configuration can be changed as appropriate in accordance with thearrangement of the component provided on the FPC that is used as thesubstrate 50 of the embodiment of the present invention, and thecomponent may be provided on only one of the first portion 51 and thesecond portion 52. The support member may be provided on the connectionportion 53 or the like.

The electromagnetic wave as the detection target is not limited to thelight or laser light from the light emitting diode. The electromagneticwave as the detection target may be invisible light such as an infraredray or an ultraviolet ray, an X ray, or the like. The detection targetmay be a magnetic force. In this case, the generator generates amagnetizing field and a magnetic field by the magnetic force. Thedetector detects changes related to the magnetic force, which occur dueto changes in the physical amount in the detection region (for example,passage of an object), to perform the sensing. In a case where thedetection target is the magnetic force, a change in the detection regioncan be detected according to a change in the magnetic force. Other thanthe electromagnetic wave and the magnetic force, the detection targetmay be, for example, an acoustic wave such as an ultrasonic wave, an ionsuch as plasma, or a cathode ray (an electron ray). The detection targetmay be anything that is changed due to a change in the physical amountof the configuration provided in the detection region.

The change in the physical amount may be a change due to a linear motionof a linear motion body existing in the detection region. In this case,the linear motion of the linear motion body can be the sensing target ofthe sensor. The sensor is capable of functioning as a linear encoder.Specifically, a change in the detection target, which occurs due to aconfiguration (for example, the scale or the like) being linearly movedrelatively with respect to the first portion 51 and the second portion52 in the detection region, is detected by the detector, and thus, thesensor functioning as the linear encoder senses the linear motion of theconfiguration. Thus, the presence or absence of the motion of the linearmotion body connected to a detection encoder, and a motion positionthereof can be detected according to the embodiment of the presentinvention. Furthermore, in a case where the motion body is a rotatingbody (the optical scale 11 attached to the end portion of the shaft 12)in the same manner as the embodiment described above, a portion in thevicinity of the shaft 12 does not enter the region (the detectionregion), and thus, a portion entering the region is a part of the motionbody. On the other hand, in a case where the motion body is the linearmotion body, it is obvious that at least a part of the motion bodyenters the region. In addition, the entire motion body may enter theregion (for example, it may pass through the inside and the outside ofthe region), according to the region of the movement that can beperformed by the linear motion body. Thus, the motion body may be anymember of which at least a part is moved in the region between thegenerator and the detector.

The invention claimed is:
 1. A sensor comprising: a generator configuredto generate a predetermined detection target; a detector configured todetect the detection target generated by the generator; a substrateprovided with the generator and the detector, the substrate including afirst portion, a second portion, a bent portion, and a ground pattern;an optical scale that rotates in a detection region between thegenerator and the detector; a stator that has a cylindrical body andthat houses the substrate and the optical scale, wherein the groundpattern is provided in a portion including: the first portion providedwith the generator; the second portion provided with the detector; andthe bent portion that is bent between the first portion and the secondportion, wherein, in the ground pattern, a ground pattern of the bentportion is narrower than: a ground pattern of the first portion providedwith the generator, and a ground pattern of the second portion providedwith the detector that faces the generator in a direction perpendicularto the first portion, wherein the stator comprises: a first memberfixing one of the first portion and the second portion; a second membermovably supporting the optical scale; and a cover to close an opening ofthe second member, wherein the first member has two support membersopposing each other to insert the one of the first portion and thesecond portion, wherein each of the two support members have: anarc-shaped inner circumference that is in contact with an outercircumference of the one of the first portion and the second portion;and an arc-shaped outer circumference that is along an innercircumference of the second member body, and wherein the opening isprovided to insert, along a direction perpendicular to a rotation axisof the optical scale; the two support members; and the substrate ofwhich one of the first portion and the second portion is fixed to thefirst member.
 2. The sensor according to claim 1, wherein the substrateincludes a connection portion connecting the first portion and thesecond portion together, and wherein the bent portion is providedbetween the connection portion and the first portion, and between theconnection portion and the second portion.
 3. The sensor according toclaim 2, wherein the ground pattern is further provided in a portionincluding the connection portion, and wherein, in the ground pattern,the ground pattern of the bent portion is narrower than a ground patternof the connection portion.
 4. The sensor according to claim 1, whereinthe substrate is a flexible printed circuit.
 5. The sensor according toclaim 1, wherein the sensor is a rotary encoder.
 6. A sensormanufacturing method, which is a manufacturing method of a sensorincluding a generator configured to generate a predetermined detectiontarget, a detector configured to detect the detection target generatedby the generator, a substrate provided with the generator and thedetector, an optical scale that rotates in a detection region betweenthe generator and the detector, and a stator that has a cylindrical bodyand that houses the substrate and the optical scale, the methodcomprising: a step of preparing the substrate including a first portion,a second portion, a bent portion, and a ground pattern, a step ofpreparing the ground pattern provided in a portion including: the firstportion provided with the generator; the second portion provided withthe detector; and the bent portion provided between the first portionand the second portion; a step of bending the substrate in the bentportion; a step preparing the stator comprising: a first member fixingone of the first portion and the second portion; a second member movablysupporting the optical scale; and a cover to close an opening of thesecond member, the first member having two support members opposing eachother to insert the one of the first portion and the second portion, andeach of the two support members having: an arc-shaped innercircumference that is in contact with an outer circumference of the oneof the first portion and the second portion; and an arc-shaped outercircumference that is along an inner circumference of the second memberbody; and a step of inserting the two support members and the substrateof which one of the first portion and the second portion is fixed to thefirst member, to the opening, along a direction perpendicular to arotation axis of the optical scale, wherein, in the ground pattern, aground pattern of the bent portion is narrower than: a ground pattern ofthe first portion provided with the generator; and a ground pattern ofthe second portion provided with the detector that faces the generatorin a direction perpendicular to the first portion.